1. Field of the Invention
This invention relates to connectors for coupling tubes and is particular although not exclusively applicable to connectors for coupling tubes to bosses on vessel walls.
2. Description of the Invention
In our European Patent Specification No. 0756125 we describe and illustrate a tube connector which is preferably formed in plastics and which has a coupling body formed with a socket containing a collet device for receiving and locking an end of a tube in the coupling body. The coupling body has a spigot at the other end of the body which could be provided with an encircling steel grab ring for engaging and holding the spigot in a thin-walled plastic sleeve or boss to which the coupling body is to be connected. One example of such an application is a vehicle fuel tank formed in plastics with an integral moulded boss on the tank to receive a connector for securing a tube to the tank. Such tanks which are supplied to the car manufacturer are invariably complex assemblies including fuel feed/return lines, vapour recovery and other "plumbing" fitments already attached ready for coupling to the various services of the vehicle. In current designs, such further components are hot-plated moulded to the tank but this has obvious restrictions, particularly where the tank is formed from high density polyethylene (HDPE) because it is only possible to weld high density polyethylene to high density polyethylene.
A further difficulty is that high density polyethylene tends to swell in contact with fuel as much as up to three percent and so any coupling to the tank must control or allow for this.